With development of a flexible display for a smart phone, a tablet computer, etc., a support is provided for supporting such flexible display in a flat state or a bent state. A conventional support may include two support plates for supporting two opposite segments of the flexible display, and the support plates may be connected by a plurality of hinge members or other else to permit the support plates to be angularly movable relative to each other so as to allow the flexible display to be bendable with the support. Thus, there is a need to provide a positioning mechanism for positioning an angular relationship between the support plates.